n3he: a measurement of parity violation in the capture of ...crawford/n3he/mainspace/files/conf -...
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Introduction Motivation Spallation Neutron Source Apparatus Current Status
n3He: A Measurement of Parity Violation in theCapture of Cold Polarized Neutrons on He-3
Mark McCreaUniversity of Manitoba
for the n3He Collaboration
October 24
Canadian Contributions Supported with Funding Provided byNSERC and CFI
n3He: A Measurement of Parity Violation in the Capture of Cold Polarized Neutrons on He-3Mark McCrea University of Manitoba for the n3He Collaboration
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Introduction Motivation Spallation Neutron Source Apparatus Current Status
1 Introduction
2 Motivation
3 Spallation Neutron Source
4 Apparatus
5 Current Status
n3He: A Measurement of Parity Violation in the Capture of Cold Polarized Neutrons on He-3Mark McCrea University of Manitoba for the n3He Collaboration
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Introduction Motivation Spallation Neutron Source Apparatus Current Status
Introduction
~n +3He → p + T + 765keV
Beam n 3He pθs,~k
T
n3He probes the low energy strong interaction, using the weakinteraction by measuring the parity violating directional asymmetryin the proton recoil from the reaction
n3He: A Measurement of Parity Violation in the Capture of Cold Polarized Neutrons on He-3Mark McCrea University of Manitoba for the n3He Collaboration
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Introduction Motivation Spallation Neutron Source Apparatus Current Status
Theoretical Motivationq
q
q
q
g
Strong Interaction
q
q
q
q
Z 0,W±
Weak Interaction
u d d
u d d
udd
udd
?
Uncertain HWI
N
N
N
N
PC
Strong
PV
Weak
π, ρ, ω
DDH Parameterization
DDH Meson Exchange Parameters:
Opv = a1πh
1π + a0
ρh0ρ + a1
ρh1ρ + a2
ρh2ρ + a0
ωh0ω + a1
ωh1ω
n3He: A Measurement of Parity Violation in the Capture of Cold Polarized Neutrons on He-3Mark McCrea University of Manitoba for the n3He Collaboration
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Introduction Motivation Spallation Neutron Source Apparatus Current Status
Esimation of the n3He ObservableFrom a full four-body calculation of strong scattering wavefunctions
• A~n,3He
p (th.) ≈ (−9.4→ 2.5)× 10−8
• n3He aims to measure this to 2× 10−8
DDH Weak (APZ )n3He → tp
Coupling
a1π −0.189
a0ρ −0.036
a1ρ 0.019
a2ρ −0.006
a0ω −0.0334
a1ω 0.0413
M. Viviani, R. Schiavilla, Phys. Rev. C. 82 044001 (2010)L. Girlanda et al. Phys. Rev. Lett. 105 232502 (2010)
n3He: A Measurement of Parity Violation in the Capture of Cold Polarized Neutrons on He-3Mark McCrea University of Manitoba for the n3He Collaboration
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Introduction Motivation Spallation Neutron Source Apparatus Current Status
Importance of the n3He Experiment
Ap = −0.189h1π−0.036h0ρ+0.019h1ρ−0.006h2ρ−0.0334h0ω+0.0413h1
ω
• ∆I = 1 are not important due to small contribution
• 4 parameters remain (h1π, h0ρ, h2ρ, h0ω)
Using:
• 18F measurement
• elastic p-p scattering at two energies
• odd-proton nuclear measurements
• NPDGamma
along with the n3He result the system can be over constrained tocheck the model.
n3He: A Measurement of Parity Violation in the Capture of Cold Polarized Neutrons on He-3Mark McCrea University of Manitoba for the n3He Collaboration
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Introduction Motivation Spallation Neutron Source Apparatus Current Status
A Brief Introduction to ParityUnder a parity transformation P polar vectors such as themomentum transform as
P(~kn)→ −~kn and P(~kp) = −~kpbut axial vectors, such as the neutron spin, remain unchanged
P(~sn)→ ~sn
Orignal State:
Beam n 3He p
θs,~k
T
Parity Transformed:
Beamn3Hep
θs,~k
T
Spin Flipped:
Beam n 3He p
θs,~k
T
n3He: A Measurement of Parity Violation in the Capture of Cold Polarized Neutrons on He-3Mark McCrea University of Manitoba for the n3He Collaboration
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Introduction Motivation Spallation Neutron Source Apparatus Current Status
Spallation Neutron Source
• Located at the Oak Ridge National Laboratory (ORNL) inTennessee
• 60 Hertz pulsed spallation source• n3He will located at the FnPB• 20K liquid hydrogen moderator for cold neutron beam lines
n3He: A Measurement of Parity Violation in the Capture of Cold Polarized Neutrons on He-3Mark McCrea University of Manitoba for the n3He Collaboration
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Introduction Motivation Spallation Neutron Source Apparatus Current Status
Neutron Pulse - Unchopped
n3He: A Measurement of Parity Violation in the Capture of Cold Polarized Neutrons on He-3Mark McCrea University of Manitoba for the n3He Collaboration
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Introduction Motivation Spallation Neutron Source Apparatus Current Status
n3He Schematic Diagram
Biological Shielding
NeutronGuide
C1 C2
M1 SMP RFSF3He Target/
Detector
HF Solendoid
n3He: A Measurement of Parity Violation in the Capture of Cold Polarized Neutrons on He-3Mark McCrea University of Manitoba for the n3He Collaboration
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Introduction Motivation Spallation Neutron Source Apparatus Current Status
FnPB Cave with NPDGamma Apparatus Installed
n3He: A Measurement of Parity Violation in the Capture of Cold Polarized Neutrons on He-3Mark McCrea University of Manitoba for the n3He Collaboration
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Introduction Motivation Spallation Neutron Source Apparatus Current Status
Prototype Monitors
Beam
HVSignal
n3He: A Measurement of Parity Violation in the Capture of Cold Polarized Neutrons on He-3Mark McCrea University of Manitoba for the n3He Collaboration
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Introduction Motivation Spallation Neutron Source Apparatus Current Status
n3He Target Chamber
Beam
HVSignal
17 HV Frames with 8 wires each16 signal Frames with 9 wires each
n3He: A Measurement of Parity Violation in the Capture of Cold Polarized Neutrons on He-3Mark McCrea University of Manitoba for the n3He Collaboration
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Introduction Motivation Spallation Neutron Source Apparatus Current Status
Proton Asymmetry in Chamber
~n +3He → p + T + 765keV
neutron proton TritonCharge Collection
revise or remove this slide, it is not complete as it currently stands.
n3He: A Measurement of Parity Violation in the Capture of Cold Polarized Neutrons on He-3Mark McCrea University of Manitoba for the n3He Collaboration
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Introduction Motivation Spallation Neutron Source Apparatus Current Status
Target Housing
• 10” conflat end flanges• windows are 1mm thick Al• 4 data feed thrus
• 2 gas feed thrus
• 2 HV feed throughsn3He: A Measurement of Parity Violation in the Capture of Cold Polarized Neutrons on He-3Mark McCrea University of Manitoba for the n3He Collaboration
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Introduction Motivation Spallation Neutron Source Apparatus Current Status
Target CAD Drawing
Frame Stack with signal and HVPCB on mount plate
Chamber exterior with allflanges in place.
n3He: A Measurement of Parity Violation in the Capture of Cold Polarized Neutrons on He-3Mark McCrea University of Manitoba for the n3He Collaboration
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Introduction Motivation Spallation Neutron Source Apparatus Current Status
Target Frames
Signal Frame
• 9 wires
HV Frame
• 8 wiresn3He: A Measurement of Parity Violation in the Capture of Cold Polarized Neutrons on He-3Mark McCrea University of Manitoba for the n3He Collaboration
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Introduction Motivation Spallation Neutron Source Apparatus Current Status
Flange Mount and Shielding
n3He: A Measurement of Parity Violation in the Capture of Cold Polarized Neutrons on He-3Mark McCrea University of Manitoba for the n3He Collaboration
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Introduction Motivation Spallation Neutron Source Apparatus Current Status
Wire Frame Alignment
• mount plate seats in flange
• 4 compression rods
• 3 point mount sets framespacing and aligment
n3He: A Measurement of Parity Violation in the Capture of Cold Polarized Neutrons on He-3Mark McCrea University of Manitoba for the n3He Collaboration
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Introduction Motivation Spallation Neutron Source Apparatus Current Status
Test Assembly of Frame Stack
• 17 HV frames
• 16 signal frames
• 144 signal wires
• approximate 14 inch height
n3He: A Measurement of Parity Violation in the Capture of Cold Polarized Neutrons on He-3Mark McCrea University of Manitoba for the n3He Collaboration
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Introduction Motivation Spallation Neutron Source Apparatus Current Status
Signal Feed Thrus and Cables
• 4 Signal Feed Thrus
• Two 25 pin Sub-D cablesper flange
• maximum 200 connections,144 used.
• kapton, PEEK, macor, andcopper materials
n3He: A Measurement of Parity Violation in the Capture of Cold Polarized Neutrons on He-3Mark McCrea University of Manitoba for the n3He Collaboration
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Introduction Motivation Spallation Neutron Source Apparatus Current Status
Current Status
• All parts are on hand.
• Frame Wiring to start end of October.
• Chamber planned to be assembled by end of year
• Testing with electronics to start next year.
n3He: A Measurement of Parity Violation in the Capture of Cold Polarized Neutrons on He-3Mark McCrea University of Manitoba for the n3He Collaboration
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Introduction Motivation Spallation Neutron Source Apparatus Current Status
n3He Collaboration
Duke University, TriangleUniversities NuclearLaboratory
• Pil-Neo Seo
Istituto Nazionale diFisica Nucleare, Sezionedi Pisa
• Michele Viviani
Oak Ridge NationalLaboratory
• Seppo Pentill
• David Bowman
University of Kentucky
• Chris Crawford
• Kabir Latiful
• Aaron Sprow
Western KentuckyUniversity
• Ivan Novikov
University of Manitoba
• Michael Gericke
• Shelley Page
• WTH. Van Oers
• Rob Mahurin
• V. Tvaskis
• Mark McCrea
Universidad NacionalAutnoma de Mxico
• Libertad Baron
University of NewHampshire
• John Calarco
University of SouthCarolina
• Vladimir Gudkov
• Young-Ho Song
University of Tennessee
• Nadia Fomin
• Geoff Greene
• S. Kucuker
• C. Hayes
University of Tennesseeat Chattanooga
• Josh Hamblen
University of Virginia
• S. Baessler
n3He: A Measurement of Parity Violation in the Capture of Cold Polarized Neutrons on He-3Mark McCrea University of Manitoba for the n3He Collaboration